package network;

import java.io.IOException;
import java.net.*;
import java.util.Scanner;

public class UdpEchoClient {
//      创建socket对象
    private DatagramSocket socket = null;
    private String serverIp;
    private int serverPort;

    public UdpEchoClient(String serverIp,int serverPort) throws SocketException {
//        客户端，系统自动分配端口号
        socket = new DatagramSocket();
        this.serverIp = serverIp;
        this.serverPort = serverPort;
    }

    public void start() throws IOException {
        System.out.println("客户端启动");
        Scanner scanner = new Scanner(System.in);
        while (true){
            System.out.println("请输入要发送的请求：");
//            1.要从控制台读取用户输入
            String request = scanner.next();
//            2.构造请求并发送
//            构造请求数据的时候，不光有数据，还要有“目标”
            DatagramPacket requestPacket = new DatagramPacket(request.getBytes(),0,request.getBytes().length,
                    InetAddress.getByName(serverIp),serverPort);
            socket.send(requestPacket);
//            3.读取响应数据
            DatagramPacket responsePacket = new DatagramPacket(new byte[4096],4096);
            socket.receive(responsePacket);
//            4.显示响应到控制器上
            String response = new String(responsePacket.getData(),0,responsePacket.getData().length);
            System.out.println(response);

        }
    }

    public static void main(String[] args) throws IOException {
//                                                     服务器与客户端在一个主机上，就固定写这个ip地址；不同主机，服务器ip在哪就写哪
        UdpEchoClient client = new UdpEchoClient("127.0.0.1",9090);
        client.start();
    }

}
